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Bacteria can be classified by their habits as they relate to human activities. The overwhelming majority of bacteria are harmless to humans. These bacteria are important to humans because they play a role in the ecology of life, by decomposing wastes, both natural and man-made, for example and created nitrogen fertilizer at the root zones of certain crops. Bacteria can also be used purposely by people to make foods. For example, the group of various bacteria collectively called the lactic acid bacteria are used for the manufacture of cultured dairy foods like sour cream. To manufacture sour cream, the species of bacteria Streptococcus lactic is added directly to the 18% cream. These bacteria grow in the cream incubated at 70 degrees producing lactic acid. The lactic acid causes the cream to thicken and cause the flavors which are ascribe to sour cream. Careful selection of the right bacterial type to be used in food manufacture has lead to a variety of cultured food, foods to which carefully selected species of bacteria have been added for their manufacture. For example, most all of our cheeses owe their unique flavors and textures to bacterial growth. San Francisco sourdough bread would not be sour (acid taste) if it were not for the lactic acid bacteria called Streptococcus sanfranciscus. growing in the dough during the time the yeast is growing and causing the dough to rise. Then there are bacterial types that are capable of spoiling foods -spoilage bacteria- or causing sickness or death in people -pathogens. These bacteria are in the minority, but they are well known. Occasionally, one species of bacteria can be categorized as either beneficial or harmful. Here's a case in point: We use bacteria called Streptococcus lactis to make buttermilk. We encourage its growth by adding it directly to the milk and allowing it to "sour" the milk--that's buttermilk. On the other hand, if our fresh milk is soured -spoiled- by these bacteria, then these bacteria are considered to be "harmful" spoilage agents. Only a few bacteria are harmful to humans. No animal alive can digest its food without the help of bacteria. Bacteria are the beginning of many food webs. Many small protists eat even smaller bacteria. Bacteria create many of our antibiotics. Bacteria, along with fungi, are the Primary Decomposers that recycle life materials and prepare them for re-use Bacteria pull nitrogen out of the air and package it so plants can use it. Without nitrogen in the soil, plants cannot grow. "You are what you eat," the old saying goes. This wisdom is true at both ends of the food curve. At one end are those couch-adhering fast food addicts who are politely described as wide bodies. At the other end are folks who puritanically monitor what they eat and what goes into the food that they consume. For them, food is serious business and often a reflection of how they live their lives. Many of us fall somewhere in between the two extremes. Not too many decades ago, lots of folks would be nearer to the deep-fried golden arches end than to the pesticide-free organic end. How times have changed. Now, at least in the developed world, more and more people are not only concerned with what they eat, but are buying foods that help them in their quest for a healthier life. The exploding popularity of functional foods - foods that are nutritionally fortified with microorganisms or compounds such as herbs and vitamins - attests to our desire to chow down on healthy food. "In 1992, the [United States functional food] market was close to nonexistent," says Thomas Aarts, executive editor of Nutrition Business Journal, a trade publication that tracks functional foods. But, according to Aarts, U.S. retail sales now top $10 billion a year and he predicts an extraordinary annual growth rate of eight to ten percent for at least the next five years. European consumers have already embraced such foods and other products to the tune of US$42 billion a year. Taking the trend to the zone of the ridiculous, you can even buy a purportedly health-enriching after-shave on your next visit to Europe! In this article we'll examine the positive roles microorganisms play in food, and discover how surprisingly ancient the roots of functional foods are. "Good" Microorganisms and Food, Part 1: Traditional Foods One of the ways many of us seek a healthier diet is to eat foods that contain or result from "good" microorganisms. As we will learn, these microorganisms - bacteria, yeasts, and moulds (fungi)- act to change the character of the food so as to provide one or more valuable outcomes. These include yummy food, nutritional oomph in each spoonful and an increased storage life. Some of these foodstuffs have been with us for centuries. Think yogurt, kefir, cheese and sauerkraut and you get the idea. Let's take a look at some of these, and other, traditional foods: A) Milk based foods Kefir, yogurt, cheese, and butter all use bacteria to acidify milk. But, like recipes in the kitchen, the presence of different ingredients - such as the strain of bacteria, other food sources that the bugs can use, the temperature, and other factors - work to produce different products. 1. Kefir Kefir is one of those microbe-containing foods that have been part of human history for centuries. Marco Polo spoke of kefir in his epic journeys through the Far East in the 13th century A.D. and in the early 19th century, kefir was in vogue at sanitariums in North America for the treatment of tuberculosis. The drink originated when Eastern nomadic shepherds accidentally discovered that fresh milk carried in leather pouches would sometimes ferment into a delicious and bubbly beverage. The word kefir likely comes from the Turkish word "Keif" meaning "good feeling", which aptly describes the sense of well-being felt by many having quaffed a glassful of the brew. The heart of kefir is the group of lactic acid bacteria known as Lactobacillus. In particular, Lactobacillus acidophilus is a mainstay of active kefir and other foods including the ever-popular fermented dairy product called yogurt, as well as sauerkraut. Lactobacillus ferments dairy products and helps preserve other foods because it makes its environment acidic in the absence of alcohol production, via the production of lactic acid. This makes the food taste sour and helps make the environment nasty for the growth of other microbes that would otherwise ruin or contaminate the food. In the Caucasus Mountains region of the Europe-Asia border between the Black and Caspian Seas, kefir is a popular drink. Perhaps coincidentally, the natives are renowned for their longevity. So, kefir may help put pep in your step. Here's a link to a site with some more information about kefir. 2. Yogurt Yogurt has also been part of the human diet for centuries, since its 'invention' in Bulgaria. Most commercial yogurt uses cows' milk and a culture of two bacteria (specific species of Lactobacillus and Streptococcus). The action of the bacteria changes the character of the milk, causing it to coagulate. Fruit can also be added to produce different tasting yogurt. Yogurt is a good illustration of the growing acceptance of good food bacteria. Canadians eat 5 times as much yogurt compared to 20 years ago. And, increasingly, "live yogurt" - yogurt that contains still-living bacteria - is becoming the yogurt of choice. Here is a great overview from the University of Guelph. 3. Cheese and Butter Cheese and butter making are other ancient crafts that rely on Lactobacillus. For cheese making, Lactobacillus lactis subspecies lactis is most commonly used. Butter-making typically utilizes another subspecies called cremoris. There is often another microbial involvement early in the process of cheese making. Milk must be changed in texture (coagulated) using a combination of enzymes that is called rennet. A form of rennet called 'vegetable' rennet is derived from certain strains of fungi and bacteria. This type of rennet is becoming very popular in the making of organic cheeses. If you'd like to learn all about making cheese, try this link: The basics of making cheese, or this site at the University of Guelph where they also have a very good overview of the microbiology (good and bad!) of milk. Moulds can also play a role in cheese making. The blue streaks that are visible in Danish Blue cheese are due to mould, and the presence of mould is often especially evident in those stinky cheeses like Camembert and Roquefort that folks either love or shrink from. The mould, which can be added along with the bacterial "starter" culture, or added to the partially complete cheese later in the process, breaks down protein. This makes the cheese creamier, even runny, in texture. B) A jug of wine, a loaf of bread and more: Yeast Like a tasty slice of freshly baked bread? A glass of wine? Or a cool brew? Then thank another good food microbe, namely the yeast called Saccharomyces. 4. Bread, Wine and Beer Yeast was the first domesticated microbe. Humans have used yeast in food preparation for millennia. For example, Egyptian hieroglyphics depict the making of bread and alcoholic beverages. Yeast was behind both of these, although at the time the processes were thought of as mysterious or magical. The very first loaf of bread or jar of brew likely arose by happenstance. But, soon after, people learned that adding a bit of saved dough or brew sediment to a new batch reproduced and sped up the magic. Likewise, learning from their mistakes, folks discovered that storage at cooler temperatures, for example, was better than storage in the hot sunshine. And so, the domestication of good food bacteria and other microbes had begun, even if their existence was not yet known. The role of yeast in yeast-leavened bread is rather more as a bystander. Those puffy loaves of bread that we eat would not be puffy at all if not for the gas produced by yeast. This gas production does not; however, impart any nutritional benefit to the bread, and in fact leavening can be done with common kitchen ingredients. So-called "quick breads" can be made by using baking soda or baking powder, which react to release carbon dioxide gas and cause the dough to rise. The process by which yeast produces gas is a result of the conversion of sugar or starch and is called fermentation. It also produces alcohol. In the case of bread making the amount of alcohol produced in rising dough is very small and even that is baked away in the oven. The Fleischmanns yeast company, by the way, has a good web page explaining the science of yeast. On the other hand the production of alcohol is sometimes the prime outcome desired by fermentation. Beer and wine are the result, and in moderation an argument can be made that they too are healthy. Contrary to popular opinion, wine, and other beverages of antiquity produced through fermentation, were probably more important in providing disease-free drinking fluids than in their tendency to intoxicate. Ancient Greeks drank their water mixed with wine, and also used wine to cleanse wounds and soak dressings. More recently, military physicians of the last century observed that during epidemics of cholera, wine drinkers were relatively spared by the disease, and troops were advised to mix wine into the water. In ancient Greece, those who drank undiluted wine would have been considered unsophisticated louts. Homer (Odyssey IX, 208f.) mentions a ratio of twenty parts water to one part wine, whereas Pliny (Natural History XIV, vi, 54) mentions a ratio of eight parts water to one part wine. The purification of water is not primarily a function of the ethanol, but rather due to other antibacterial compounds (such as "flavonoids") in the wine. Similarly, brewing of beer often led to a safer drinking alternative of otherwise contaminated water. Interestingly, beer was long considered a food rather than a drink, reflecting the fact that early beers were probably low in alcohol and full of vitamins from the yeast used to ferment grain. In the 16th and as late as 17th century, beer was given to children in the household. This so-called "small beer" contained about 2-3% alcohol. The scientific identification of yeast, as the agent of fermentation, awaited the invention of the microscope and the brilliance of Louis Pasteur. In the late 1860s, Pasteur showed that bread making and alcohol production were due to the action of yeast. Commercial use of various strains of yeast was not far behind. 5. Vinegar, Pickles & Sauerkraut Once wine was discovered, vinegar was not far off. Vinegar literally means sour wine (although vinegar can be made from many other things than just wine) and is the result of the activity of one more bacterium (Acetobacter), which converts ethanol to acetic acid. The acid prevents the growth of other bacteria, and this property was recognized as seen in references to the use of vinegar as a wound dressing in Roman times. Here is a web site dedicated to vinegar. Pickling is simply the ancient craft of preserving foods in salt brine and/or vinegar. Before refrigeration was common pickling was an essential way to preserve vegetables and ensure that winter or sea voyagers diets stayed nutritious and full of vitamins. There is a really wonderful site dedicated to food science, and in particular the science of pickling. I recommend that you consider www.exploratorium.edu/cooking/pickles/index.html as well as the page detailing the combination of salt in the pickling mix, which contributes to the prevention of growth of "bad" microorganisms. Just as vinegar is derived from the French words for sour wine, we have "sauerkraut" - German for ''sour cabbage''. Sauerkraut, though usually thought of as a German food, has actually been traced back to food for workers building the Great Wall of China more than 2,000 years ago. In the Chinese version this food is made from shredded cabbage fermented in rice wine, European style sauerkraut is made by shredding cabbage, adding salt and sometimes spices, and allowing the mixture to ferment. The fermentation process depends on the normal mix of bacteria found on cabbage leaves and uses the salt mix to promote the growth of those specific "good" bacteria that will produce lactic and acetic acid. Not only does sauerkraut allow one to preserve cabbage through long winter seasons, it's full of vitamins, including vitamin C. In fact, it wasn't limes that first prevented scurvy on English ships undertaking long sea voyages; it was sauerkraut. This site, dedicated to the history of the Peace River Region of British Columbia and Alberta has a nice article about sauerkraut in "the good old days". 6. Marmite and Vegemite Not only have yeasts helped us to make and preserve other foods, they have become foods themselves. From England comes marmite and in Australia, vegemite. Both of these products are nutritious pastes, often had for breakfast on toast or bread. With a taste that is best described as "distinctive" for palettes raised on peanut butter, these two products are made from spent brewers yeast that was previously discarded. It was a German chemist, by the name of Liebig, who found that this yeast could be made into a concentrated vitamin rich food product. "Good" Microorganisms and Food, Part II: Probiotics The new face of an old tradition While the use of such good food microbes has been around for millennia, it is not that long ago that we began to figure out how they did what they did. In the early years of the twentieth century, Eli Metchnikoff, one of the titans of microbiology, studied the benefits of lactobacilli in the intestinal tract. After this promising start, however, research lagged, until about 20 years ago, when the market potential of microbially-enriched foods became evident. In recent decades, the use of microbes to produce food that is better for us has become popularized using the buzz word "probiotics". As defined by the Food and Agriculture Organization of the United Nations and the World Health Organization in October, 2001, probiotics "are live microorganisms which when administered in adequate amounts confer a health benefit on the host". The potential of probiotics as healthy foods has caught the attention of the FAO/WHO who have produced an interesting publication indicating the possible good impacts of such foods, while interjecting a cautionary note regarding some of the rather more fantastic unproven claims. (Joint FAO/WHO Expert Consultation on Evaluation of Health and Nutritional Properties of Probiotics in Food Including Powder Milk with Live Lactic Acid Bacteria, October 2001 (download the full pdf report file here)) The distinction between traditional microbe-containing food and probiotics is hazy. For example, the tradition of eating yogurt and kefir (fermented milk with live bacteria) is centuries-old. Yet, these foods have never been subjected to rigorous testing to prove their beneficial health effects, in contrast to probiotics, which must leap through regulatory hoops prior to marketing. So, in that sense, the traditional foods are not probiotics. On the other hand, some yogurts have bacteria added just prior to packaging with the deliberate aim of bettering the health of those who consume it. These are indeed probiotics. Several possible mechanisms have been proposed to explain the beneficial effects of a probiotic diet. These, include the production of compounds that stop other bacteria from growing, out competing bacteria for living space or food on the walls of the intestines, production of enzymes (e.g., ß-galactosidase, amylase) that aid in digestion, reducing the amount of "bad" cholesterol in the blood, and stimulation of the immune system. The last suggestion is garnering lots of attention now. For example, studies in animals have shown that Lactobacilli and Bifidobacteria can stimulate the pumping out of antibacterial chemicals into the intestinal tract. Whether all these benefits, indicated by laboratory studies, actually occur in the real world of the human gut is still debatable. Answers may not be forthcoming, since human trials would be difficult to perform. The rationale for good microorganisms in foods is grounded in the reality that we are to a large extent full of microorganisms - many are the same species that are ingested as part of a probiotic diet. We are crammed with some 1014 bacteria. To put that number into a realistic perspective, there are about 6.4 billion (109) people alive on Earth. So each of us is carrying around a bacterial population equivalent to around 100,000 times the population of the Earth. This microbial population of the mucous membranes (the mouth and lower intestinal tract for example) is essential to the maintenance of our health by fending off disease causing bacteria and producing essential vitamins. But, if this balance is affected, by say antibiotics, other microbial invaders can gain the upper hand. One example of many is the condition called antibiotic-associated colitis (serious inflammation of the colon). A bacterial strain called Clostridium difficile is normally found in the intestines of 5% of healthy adults, but people can also pick up the bacteria while they are in a hospital or nursing home. In a healthy person, the harmless normal gut bacteria jostle for food and a place to live along the intestinal wall. Potential invaders do not have any room or food. When antibiotics are given, however, most of the resident bacteria are killed. With fewer bacteria to compete with, the normally harmless Clostridium difficile grow rapidly and produce toxins that damage the intestinal wall. Gregor Reid is a Professor at the University of Western Ontario, London, and Director of the Canadian Research and Development Centre for Probiotics. Reid has been championing probiotics for over a decade. He asks, ""When was the last time we did anything for the beneficial bacteria that keep us alive?" He is passionate about the need for microbiologically enhanced foods as a way of helping us become healthier. This is particularly true in hospitals, where some therapies that destroy invading bacteria also wipe out the natural protective microbial flora. "Why do we annihilate bacteria with antimicrobials then expect hospital food to replenish the patient before discharge?" says Reid. In the past 20 years, societal attitudes toward microbial enhancement of foods have undergone what Reid describes as a "quiet revolution." Continues Reid, "I say 'quiet' only because many traditional scientists, agencies and industries have turned somewhat of a blind eye to it. Thus, until the past few years it never reached the radar screen. The change has been quite dramatic." Publication statistics underscore the point. In the past 5 years, more than 1000 peer-reviewed papers on probiotics have been published, while over the preceding 20 years fewer than 100 papers on probiotics were published. Europe has embraced foods that contain "good" bacteria much more so than have consumers in North America. Strains of Lactobacillus and Bifidobacterium are used to fortify drinks, cheese, and milk with living bacteria by a number of European companies. The manufacture and marketing of these fermented dairy drinks is a robustly competitive field. The US$350 million annual market has companies such as Clesa (Spain), Parmalat (Italy), Skäne Mejerier and Ojas (Sweden), and market leader Danone (France) all carving out a niche. A Japanese company called Yakult launched a line of microbiologically fortified dairy drinks in Europe in 1995. The centerpiece of the company's product line is a fermented milk drink that contains hundred of millions of a bacterium called Lactobacillus casei Shirota strain. The bacteria can survive the acidic conditions of the stomach, and so can reach the small intestine. There they help maintain the balance of healthy bacteria. Sales of Yakult have soared to some 9.5 billions unit per year. A few years ago, the company produced a brochure on the 'nuts and bolts' of probiotics. The interest was overwhelming: over 500,000 people from the UK alone requested brochures! The "good" microorganisms create a chemical environment that inhibits the "bad" microorganisms. They also compete for food with the "bad" infective organisms. If a woman takes antibiotics to treat an infection, whether it is for vaginitis or not, the antibiotics kill both the bad and the good microorganisms, ultimately creating various imbalances in the body, including yeast infections. Bacteria are very small. There are more bacteria in your mouth than there are people who have ever lived. The polluted water containing the "bad" microorganisms are sprayed over a media containing the "good" microorganisms. These microorganisms will "eat" or destroy the harmful organisms. After the harmful microorganisms are destroyed, the water then leaves media to be disinfected using chlorine. Disinfecting the water ensures the water is clean of both "good" and "bad" microorganisms. The disinfected water is then sent back to the environment to be reused. Most everyone is familiar with the instances of food poisoning. One of the most common is caused by a bacterium called Staphylococcus aureus, an organism that produces a heat-stable toxin during its growth in some foods. When a food containing the toxin produced by these bacteria is consumed, the person becomes very sick for 24 to 48 hours. However, death rarely results. There have been cases of food poisoning of this type from eating dairy products. The point here is that although these staph bacteria are killed by pasteurization, the toxin is not destroyed. Thus, control of the growth of the bacterium is essential, for if it allowed to grow in food, it could produce the toxin. Of course, the best control is to keep the organism out of the food in the first place. That's why we wash hands after leaving the restrooms, wash and sanitize equipment that comes in contact with food, etc. Obviously, the food industry is doing a great job at keeping this and other food-poisoning bacteria from processed foods since but 5% of food poisoning problem originate at the food processing plant. Among the pathogenic bacteria that cause disease in man are Brucella abortus, which causes undulant fever, and various species of Salmonella which cause a disease called salmonellosis. It should be remembered that various food poisoning and pathogenic bacteria can inhabit the udder of a cow, and some can cause illness in people if the milk is consumed unpasteurized. There is no assurance that cow or goat milk that is tested and shown to be pathogen free on one day cannot acquire harmful bacteria the next day. Frequently, there is no outward sign in the cow that indicates that this has occurred. Some bacteria are very useful and are used in food manufacturing e.g. yoghurt, cheese. Other useful bacteria are found naturally in the human gut and help us to digest food. However certain bacteria are responsible for causing food poisoning. These bacteria are known as pathogenic bacteria and while many of them are destroyed during cooking, some of them may produce spores and toxins that can survive high temperatures and re-contaminate our food as it cools. There are several types of bacteria that cause food poisoning. Most people know of Salmonella associated with raw poultry and eggs. It causes severe stomach pain and diarrhoea within 12 to 36 hours of eating contaminated foods. Another type of bacteria, Staphylococcus aureus, is carried in the nose, mouth and on the hands of people. It causes nausea and vomiting within I to 6 hours of eating food. Yet another bacteria, Clostridium perfringens, is carried in raw vegetables and raw meats. One thing to be sure of is that these bacteria are likely to be present in one form or another in the kitchen. Gut Flora Balance It is estimated that the human intestine contains more that 400 different bacterial species and approximately 100 trillion bacterial cells, which is more than ten times the number of cells comprising the human body. The intestines of man and animals have both beneficial or good microorganisms and pathogens or bad microorganisms. These populations of organisms wage are constantly competing with each other in order to maintain a proper balance. The unfriendly pathogenic microbes are beneficial to the ecology of the intestines when they are in the minority and in balance with the friendly beneficial bacteria. When pathogenic microbes significantly outnumber the beneficial ones, health problems result. For optimum "gut flora balance," the beneficial bacteria should predominate, presenting a barrier to invading pathogenic organisms. Approximately 85% of the intestinal microflora in a healthy person should be beneficial bacteria and 15% pathogenic bacteria. In plain English…….similar to facts about cholesterol, there are the good and bad bacteria. The intestine has good “friendly” bacteria and bad “unfriendly” bacteria. These bacteria, occupying the same GI space in your intestine, must find ways to get along. GI disease in the form of IBS and its myriad of symptoms, including gas-pain- cramps- abdominal pains, chronic diarrhea and or alternating bouts of diarrhea and constipation are the result of an imbalance in the GI tract of these bacteria. Probiotics Over the past few years it has become increasingly clear to GI researchers and physicians that “probiotics” have powerful therapeutic properties in a number of GI disorders. In addition to these positive properties, probiotics have fewer side effects and are cheaper than many prescription medications on the market. In light of these facts, investigators have begun studying the effect of probiotics in a host of diseases. BioBalance believes this is the beginning of a quantum shift in the approach to GI disease. The approach allows for the use of probiotics alone as well as additive therapy to any other treatment the patient may be taking. While some bacteria are harmful are cause diseases, other bacteria do useful things like help clean up sewage or oil spills. Bacteria can come from improperly treated sewage, runoff from animal wastes and industrial sources such as slaughter hours, food and paper processing plants, and some landfills. Bacteria reduces that amount of oxygen in the water. Lack of oxygen hinders the water’s ability to support aquatic animal and plany life. Bacteria can also be a source for the spread of some diseases in the water. These diseases can be spread to aquatic wildlife and plants and possibly even to human beings. Antibiotics can be especially disruptive to intestinal flora because they destroy beneficial bacteria along with harmful ones. Without enough "good" microorganisms, "bad" bacteriathat are resistant to the antibiotic you receivedgrow out of control, producing toxins that can damage the bowel wall and trigger inflammation. The bacterium responsible for almost all cases of pseudomembranous colitis and many instances of severe AAD is Clostridium difficile. A small percentage of healthy people have C. difficile in their digestive tracts, but most people acquire the bacteria during a stay in a hospital or nursing home. It's likely that many hospitalized patients are exposed to C. difficile, but the bacterium causes problems only in people treated with antibiotics. Then it grows out of control, leading to severe diarrhea and potentially life-threatening complications. Your mouth is teeming with microorganisms — as many as 500 different species of fungi, viruses and bacteria. In fact, a healthy mouth can contain anywhere from 1,000 to 100,000 bacteria per tooth. Most of these bacteria are beneficial, helping to break down food and protecting you from harmful microorganisms. A few, such as Streptococcus mutans, the bacterium that causes tooth decay, can be extremely destructive. In a healthy mouth, however, the good microorganisms normally keep the bad ones in check. But in trench mouth, harmful bacteria grow out of control — first inflaming your gums and eventually damaging or destroying the delicate gum tissue (gingiva) that surrounds and supports your teeth. Large ulcers, often filled with bacteria, food debris and decaying tissue, may form on your gums, leading to severe pain, bad breath and a foul taste in your mouth. In time, as gum and bone tissue is destroyed, you may lose some of your teeth. Nutritional deficiencies, poor oral hygiene, tobacco use, emotional stress and a compromised immune system can all change the environment in your mouth, leading to an overgrowth of harmful bacteria. Doctors don't fully understand how these bacteria destroy gum tissue, but certain substances, including enzymes and toxins, produced by the bacteria may play a role.
What Is Microbiology?
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